# Acquired Hemophilia A Presenting as a Spontaneous Soft Tissue Hematoma in an Elderly Male

## TL;DR

An elderly man with a hip replacement developed a spontaneous blood clot mistakenly thought to be an infection, later diagnosed with a rare autoimmune bleeding disorder.

## Contribution

This case highlights the diagnostic challenges of acquired hemophilia A and emphasizes the need to consider it in unexplained bleeding.

## Key findings

- A 60-year-old male presented with a spontaneous intra-articular hematoma initially misdiagnosed as a periprosthetic infection.
- The patient was later diagnosed with acquired hemophilia A after hematology evaluation revealed autoantibodies against factor VIII.

## Abstract

Acquired hemophilia A (AHA) is a rare but potentially life-threatening autoimmune bleeding disorder characterized by autoantibodies against factor VIII. It often presents with spontaneous bleeding in patients without a personal or family history of coagulopathy, making diagnosis particularly challenging. We present a case of a 60-year-old male with a remote history of right total hip arthroplasty (THA) who developed a spontaneous intra-articular hematoma, initially mistaken for a periprosthetic infection. He later re-presented with expanding ecchymosis and anemia, ultimately diagnosed with AHA following hematology evaluation. This case highlights the diagnostic pitfalls and emphasizes the importance of considering acquired coagulopathies in unexplained bleeding.